Generally, a liquid crystal display (LCD) panel includes a thin film transistor (TFT) substrate, a substrate opposite to the TFT substrate, and a liquid crystal layer between the TFT substrate and the opposite substrate. A TFT substrate can include a TFT array having a plurality of TFTs, each of which includes a gate, a source, a drain, and a channel layer coupling the source to the drain. Semiconductive materials, such as metal oxides, are widely used to make the channel layer.